Effect of Impurities on Tertiary Recrystallization in Thin 3% Silicon Steel Sheets

It is well known that very thin (<100 μm) grain oriented silicon steel sheets having lower iron losses than iron-based amorphous materials can be made by using tertiary recrystallization. In this study, the relation between impurities and the tertiary recrystallization behavior was investigated.The main findings are as follows:(1) The tertiary grain growth of the samples with less impurities is observed on annealing at a lower temperature and for a shorter time than that of the sample without purification. It was shown that Cu is the dominant element for the inhibition of tertiary recrystallization.(2) Using the sample having less Cu content, the tertiary recrystallization is observed by annealing in hydrogen atmosphere.(3) With decreasing content of impurities, the size of a tertiary grain becomes smaller. But the preferred grain orientation of (110)[001] is not changed with the amount of impurities.